TMEM119 and Alzheimer disease: TMEM119 is highly expressed on subclusters of microglial cells with more homeostatic properties, and this subcluster is partly lost with increasing age and in neurodegeneration as observed in Alzheimer's disease and amyotrophic lateral sclerosis brain tissue (Chiu et al., 2013; Holtman et al., 2015; Krasemann et al., 2017; Olah et al., 2018; Orre et al., 2014).